Inkjet printers have become increasingly inexpensive and increasingly popular. A typical inkjet printer usually has a number of common components, regardless of its brand, speed, and so on. There is a print head that contains a series of nozzles used to spray droplets of ink onto paper. Ink cartridges, either integrated into the print head or separate therefrom, supply the ink. There may be separate black and color cartridges, color and black in a single cartridge, a cartridge for each ink color, or a combination of different colored inks in a given cartridge. A print head motor typically moves the print head assembly back and forth horizontally, or laterally, across the paper, where a belt or cable is used to attach the assembly to the motor. Other types of printer technologies use either a drum that spins the paper around, or mechanisms that move the paper rather than the print head. The result is the same, in that the print head is effectively swept across the paper linearly to deposit ink on the paper. Rollers pull paper from a tray, feeder, or the user's manual input, and advance the paper to new vertical locations on the paper.
In general, there are two broad classes of inkjet printers: continuous-ink inkjet printers, and drop-on-demand inkjet printers. The earliest inkjet printers were continuous-ink printers. With this type of inkjet printer, a continuous stream of ink droplets is sprayed. Deflection plates are used to cause the ink to either reach the media, or drop in a return gutter. The inkjet nozzle typically uses a piezoelectric crystal to synchronize the droplets, and a charging tunnel selectively charges the droplets that are deflected into the return gutter. Other droplets reach the media. Most inkjet printers today, however, use the drop-on-demand approach, which forces a droplet of ink out of a chamber by heat or electricity. The thermal method is used by some manufacturers, in which a resistor is heated that forces a droplet of ink out of the nozzle by creating an air bubble in the ink chamber. By comparison, the electric approach employed by other manufacturers uses a piezoelectric element that charges crystals that expand and jet the ink onto the media.
Existing inkjet printers, however, can sometimes be susceptible to failure in their print head mechanisms that contain the inkjet nozzles. In the case of thermal ink droplet ejection, the heat must be precisely controlled to ensure proper printing. However, the use of heat can be unpredictable, in that ink bubbles and other undesirable artifacts may occur. The heat itself must also be taken into account when designing the nozzles and the other components of the print head mechanisms, because the heat can cause these components to fail. Cooling mechanisms may thus be necessary to ensure the prolonged life of the print head mechanisms. In the case of electric ink droplet ejection, the electrical components are typically in direct contact with the ink, which can render the components prone to failure. For these and other reasons, therefore, there is a need for the present invention.